WPF defines a set of resource keys to be used for the template definition of the different MenuItem roles:

• <ControlTemplate x:Key="{x:Static MenuItem.TopLevelHeaderTemplateKey}" TargetType="MenuItem">
• <ControlTemplate x:Key="{x:Static MenuItem.TopLevelItemTemplateKey}" TargetType="MenuItem">
• <ControlTemplate x:Key="{x:Static MenuItem.SubmenuHeaderTemplateKey}" TargetType="MenuItem">
• <ControlTemplate x:Key="{x:Static MenuItem.SubmenuItemTemplateKey}" TargetType="MenuItem">

So they can be used in MenuItem style definition and allow restyling several roles of MenuItem without having to restyle all of the control:

<Style TargetType="{x:Type MenuItem}">

<Setter Property="HorizontalContentAlignment" Value="{Binding HorizontalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>

<Setter Property="VerticalContentAlignment" Value="{Binding VerticalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>

<Setter Property="Background" Value="Transparent"/>

<Setter Property="BorderBrush" Value="Transparent"/>

<Setter Property="BorderThickness" Value="1"/>

<Setter Property="ScrollViewer.PanningMode" Value="Both"/>

<Setter Property="Template" Value="{DynamicResource {x:Static MenuItem.SubmenuItemTemplateKey}}"/>

<Style.Triggers>

<Trigger Property="Role" Value="TopLevelHeader">

<Setter Property="Background" Value="Transparent"/>

<Setter Property="BorderBrush" Value="Transparent"/>

<Setter Property="Foreground" Value="{StaticResource Menu.Static.Foreground}"/>

<Setter Property="Template" Value="{DynamicResource {x:Static MenuItem.TopLevelHeaderTemplateKey}}"/>

<Setter Property="Padding" Value="6,0"/>

</Trigger>

<Trigger Property="Role" Value="TopLevelItem">

<Setter Property="Background" Value="{StaticResource Menu.Static.Background}"/>

<Setter Property="BorderBrush" Value="{StaticResource Menu.Static.Border}"/>

<Setter Property="Foreground" Value="{StaticResource Menu.Static.Foreground}"/>

<Setter Property="Template" Value="{x:Static MenuItem.TopLevelItemTemplateKey}}"/>

<Setter Property="Padding" Value="6,0"/>

</Trigger>

<Trigger Property="Role" Value="SubmenuHeader">

<Setter Property="Template" Value="{DynamicResource {x:Static MenuItem.SubmenuHeaderTemplateKey}}"/>

</Trigger>

</Style.Triggers>

</Style>